Conventionally known foam dispensing containers discharge foam produced from a foaming liquid contained in the container body when the trunk portion of the container, which is elastic, is pressed by a human hand. In these types of foam dispensing containers, to produce foam, the foaming liquid and air must be mixed in a mixing chamber provided in a lid body. Widely used foam dispensing containers have an air opening for delivering air into the lid body from the container body and mix the foaming liquid with the delivered air to produce foam.
In a foam dispensing container disclosed in Japanese Patent No. 2934145, for example, the foam quality can be improved by delivering air into the air-liquid mixing chamber from a plurality of positions in the circumferential direction rather than from one position. In the foam dispensing container, however, since the foaming liquid is delivered from one position in the lower part of the air-liquid mixing chamber, the area of contact between the foaming liquid and air is so small that adequate mixing of the two is sometimes hindered, and foam of good quality cannot always be provided. When the container is pressed, a large amount of foaming liquid sometimes flows into the air-liquid mixing chamber at once, causing the foaming liquid to be discharged before it is sufficiently mixed with air. The uniformity and stability in foam quality have not been satisfactory. Although the foam quality has been adjusted by changing the amount of foaming liquid delivered into the air-liquid mixing chamber by changing the cross-sectional area of the flow path in the tube body, the change in the cross-sectional area of the flow path in the tube body changes the flow speed of the liquid supplied into the air-liquid mixing chamber, affecting the air-liquid mixing conditions in the air-liquid mixing chamber. The process of trial and error to find the cross-sectional area of the flow path in the tube body that provides foam of desired quality requires great effort, making it difficult to adjust the foam quality sometimes. Although a reduced cross-sectional area of the flow path in the foaming liquid inlet is expected to improve the air mixing efficiency, consequently homogenizing the foam, the foam dispensing container disclosed in Japanese Patent No. 2934145 has just a single liquid inlet and requires a greater pressing force to discharge foam, lowering the usability of the container.
In a foam dispensing container disclosed in Japanese Utility Model Publication No. H1-122851, for example, the air intake path into the air-liquid mixing chamber is formed by a gap between a pipe fixture (flow path forming portion) disposed in a pipe joint and the inner wall of a lid member. In the foam dispensing container having this type of structure, the size of the gap changes depending on how the pipe joint and the lid member are assembled, changing the cross-sectional area of the air intake flow path and causing the amount of air flowing into the mixing chamber to exceed or fall below the designed level, which prevents foam of a desired foam quality from being formed. For example, when the pipe fixture is insufficiently fitted into the lid member, the gap between them increases, increasing the cross-sectional area of the air intake flow path. This would allow a greater-than-designed amount of air to flow, lowering the foam density and making it impossible to obtain foam of desired quality. Depending on how the produced components are assembled and how the components fit together, different containers have different gaps between the pipe fixture and the inner wall of the lid member, producing variations in the cross-sectional area of the air intake flow path and in the flow of air into the mixing chamber. The foam dispensing containers having the conventional structure, represented by the one disclosed in Japanese Utility Model Publication No. H1-122851, cannot provide foam of stable quality because of the variations in the quality of discharged foam among individual containers. While the containers are being used repeatedly, the pressure applied to the components or the force exerted on the containers from the outside affects the fitting status of the components, changing the cross-sectional area of the air intake flow path and making the foam quality unstable over time.